‹‹‹ Vitr. 2.8.3 | Table of Contents | Vitr. 2.8.5 ›››
4He who is desirous that this may not happen to his work, should build his two face walls two feet thick either of red stone or of brick or common flint, binding them together with iron cramps run with lead, and duly preserving the middle space or cavity. The materials, in this case, not being thrown in at random, but the work well brought up on the beds, the upright joints properly arranged, and the face walls, moreover, regularly tied together, they are not liable to bulge, nor be otherwise disfigured.
4He who wishes to avoid such a disaster should leave a cavity behind the facings, and on the inside build walls two feet thick, made of red dimension stone or burnt brick or lava in courses, and then bind them to the fronts by means of iron clamps and lead. For thus his work, being no mere heap of material but regularly laid in courses, will be strong enough to last forever without a flaw, because the beds and builds, all settling equally and bonded at the joints, will not let the work bulge out, nor allow the fall of the face walls which have been tightly fastened together.